HVAC dampers provide a means of controlling air flow through air handling duct systems. Dampers may comprise a single damper blade or multiple damper blades. Damper blades maybe either circular, rectangular or other shape as may suit a designer.
Damper blades require seals to optimize system efficiency. Leakage includes gas flow around the damper blade which can cause volumetric or temperature related system problems.
Seals may comprise a metallic strip which is pressed between the damper blade and an adjacent sealing surface such as a damper frame or body. While effective in many situation such a design offers little in terms of being an effective thermal barrier.
In certain applications there can be a significant temperature differential which can cause loss of heating or cooling energy across the damper, for example, a damper discharging to the exterior of a building during cold or hot conditions. In such conditions the single strip seal is inefficient leading to excessive heating or cooling upstream of the damper, or condensation on the damper which can lead to premature failure.
Representative of the art is U.S. Pat. No. 4,545,566 which discloses metal seals for damper blades, preferably made of sheet metal, as well as the combination of the blade with the metal seal. The damper blade is pivotably mountable and has longitudinally extending edges which are formed to define a groove spaced from and close to the longitudinal edge of the blade and parallel thereto. The metal seal is constituted by a rolled strip of metal formed to include a pair of opposite sides and a bottom defining a U-shaped portion, a hook portion extends inwardly from the free end of one of said sides toward the bottom of the U, and a sealing flap is reversely bent to extend away from the end of the other of said sides. In use, the U-portion of the seal is forced onto the grooved edge until the free end of the hook portion snaps and locks into the groove.
What is needed is a damper a first seal and a second seal disposed to cooperatively engage an adjacent first blade end portion and second blade end portion such that a dead air space is created between the adjacent first seal and second seal in a damper closed position, and a first thermal gap and a second thermal gap disposed within said dead air space in the damper closed position. The present invention meets this need.